Quick and Easy 400 Phase Inverter Adjust.

Discussion in 'Fisher Forum Stickies' started by larryderouin, Dec 1, 2013.

  1. larryderouin

    larryderouin Do I get Food, Med's, or more gear this Month? Subscriber

    Messages:
    19,979
    Location:
    Glen Burnie Md.
    I'm currently working on a 400 Serial 51868U
    ( http://www.audiokarma.org/forums/showthread.php?t=559395 ) but have no scope. So I asked Dave Gillespie if there was a way to adjust the P.I. without the aid of a scope and not involving math higher than 7th grade.

    Dave came to the rescue! He actually came up with 2 ways of doing it, although the 1st involves some math (no real way of getting around it), and it works. I found the 2nd option a faster and easier way to do it, and really even a Caveman can do it.

    With BOTH OPTIONS the Unit under adjustment is UNPOWERED and UNPLUGGED! REMEMBER ! UNPLUG IT FROM THE WALL.
    The Resistor # in parenthesis is the RIGHT CHANNEL. Unparenthesis is LEFT CHANNEL!

    Resistor #'s are based on the 48001 and up manual. Units with a serial # lower than 48001 will use the 20001 and up manual. From what I understand the 20001-29999 manual follows the 10001-19999 manual for part numbering. My copy of the 10001 manual does NOT have a schematic. But the parts lists match up for these parts and the caps below in the improved option.

    48001.......20001
    R110 = R87 Right Channel
    R116 = R97 Right Channel
    R109 = R86 Left Channel
    R115 = R96 Left Channel

    THESE INSTRUCTIONS ARE FOR THE 400. For OTHER MODELS SEE the note dated 10-17-14 for clarification and further instructions.

    1st OPTION...
    1.) Measure and record the value of R110(R109).

    2.) Disconnect one end of R116(R115). Measure R116(R115) and record. Do not reconnect yet.

    3.) Determine what value resistance when in parallel with measured value of R116(R115) equals the measured value of R110(R109).

    4.) Place ohm meter from pin #3 of phase inverter to ground.

    5.) Adjust phase inverter for value determined in step #2.

    6.) Reconnect R116(R115).

    NEW AND IMPROVED way, and the way I did it. This involves no desoldering, soldering, or math. Just a DMM and a Jumper wire with 2 alligator clips. AGAIN! TURNED OFF AND UNPLUGGED!!!!

    NOTE: PART #'s change due to SERIAL #'s.
    For those having units with serials of 29999 and below, the relevent part #'s the B+ to Ground is C75C.
    For those having units with Serials 48001 and above, the relevent part # of the B+ to Ground is C52C.
    It's the SAME PART Just uses different part # on the schematics.

    1.) Using an alligator clip lead, short the B+ supply point to the phase inverter tubes to ground. This would be the 320V source that appears across C52C. This is the 4 section CAN CAP.

    2.) Ground the common lead of your ohm meter.

    3.) Measure and record the resistance value that appears at pin #1 of the left and right phase inverter tubes.

    4.) Connect your ohm meter to pin #3 of the left and right phase inverter tubes, and adjust their respective phase inverter control for the respective value noted in Step #3 above.

    5.) Remove the alligator clip lead.


    Close it up and enjoy.

    It took me 5 minutes total to adjust the PI on both sides with original pots. Actually it took me longer to clean them with DeOxit than it did to adjust them. They can be touchy but making a mark on the dial and face 1st, then spray conservatively with DeOxit, and exercise 40-50 times. Blow it dry (cool setting on lungs) and do your adjustments.


    A very Big thanks to Dave Gillespie. I hereby nominate him for FISHER Forum M.O.T.Y. Any seconds???

    Larry

    I pulled the info for the 500 and 800 models from post 19 to consolidate the info. (07/31/2014)EDIT:Changes to 400 procedure for 800-B/C and 500-B/C



    The only real changes are which can capacitor and which section of that can cap to ground to take the measurement off pin 1 of the phase inverter tubes. It's the same section. Depending on which model you have, the B+ will either be 320VDC or 350VDC.

    As the 2nd option is the most efficacious for those of us who are technically challenged, we'll use that one for all of the following models.


    POWER OFF, PLUG BAGGED!!!! (this keeps you vertical!)

    800-C STAND-ALONE SERVICE MANUAL ALL VERSIONS
    1.) Ground C87C and follow the rest of the directions. C87C is the 350V B+. (Marker B3 at capacitor and B1 at V12)

    EXECUTIVE VIII Model 950 (800-C Serial 10001-19999)
    Procedure is same as Standalone 800-C. B+ on C87C is 320V tho.

    EXECUTIVE IX Model 960 (No Serial noted on manual).
    Procedure is same as Standalone 800-C. B+ on C87C is back up to 350VDC.


    500-C 30001-49999 manual
    Ground C91C(350V B+) and follow directions outlined in POST #1


    500-B 20001-29999 manual
    Ground C78C (320V B+) and follow directions outlined in POST #1


    800-B 20001-29999 manual
    Ground C95C (320V) and follow directions outlined in POST #1

    EDIT 10-17-14 NOTE: For those with units other than the 400.
    You may find that appears that Pins 1 & 3 actions are reversed. Or 6&8 are the actionable pins, Or that on certain units (with the 7199 driver) Pin 1 & 8 are the pins used. See POST #29 by Dave Gillespie for the explanation and solutions to this. POST # 30 will LIST by MODEL which pins are which.
     
    Last edited: Jun 14, 2016
  2. notdigital

    notdigital AK Subscriber Subscriber

    Messages:
    2,215
    Location:
    NYNY

    Damn, gonna jump on that tonight :D

    And, of course, I second!!!!
     
  3. bhamham

    bhamham Super Member

    Messages:
    2,038
    Location:
    France
    Great stuff :thmbsp:

    I'll third that nomination. Great guy who spends countless hours helping others.
     
  4. HVHiFI

    HVHiFI Hudson Valley HiFI Subscriber

    Messages:
    2,106
    Location:
    Chester, NY
    Fantastic info! Thank you Dave and Larry!
     
  5. Jailtime

    Jailtime Standin' on a corner

    Messages:
    10,953
    Location:
    Velva ND
    Option #2 seems to work pretty well on a 500C. :thmbsp:
     
  6. dannyr

    dannyr Active Member

    Messages:
    259
    Larry, thanks for posting this. Do you happen to know if either of these methods would work for on a 400 with Dave's upgrades? Thanks

    Also wouldn't shorting 320volts to ground be dangerous?
     
  7. larryderouin

    larryderouin Do I get Food, Med's, or more gear this Month? Subscriber

    Messages:
    19,979
    Location:
    Glen Burnie Md.
    Danny; You'd be doing this with the power OFF and the unit UNPLUGGED! Drain the cap 1st with a large value 5w Resistor until you get ZERO VOLTS.

    As far as working with Dave's upgrades, it probably would, but for backup ask Dave.

    BTW it IS noted in the procedure at least TWICE "POWER OFF and UNPLUGGED"!
     
  8. dcgillespie

    dcgillespie Fisher SA-100 Clone Subscriber

    Messages:
    8,865
    Location:
    Ball Ground, GA
    It will work, but because the phase inverter control in my modification is more directly designed to address the slight imbalance noted in the at least the AX version of the 400's OPTs, there is a slightly different, but still very easy process that can be used.

    Therefore, for those who have my modification installed, a very good setting can be had by simply adjusting the control so that the resistance measured from pin #3 to ground of the phase inverter tube, is equal to 96.2% of the value of the resistor that is connected to pin #1 of the phase inverter tube.

    And that's it.

    Danny, you asked about this some time ago, and I apologize for not responding sooner. I just haven't had any need to open my 400 up again since I installed it in my receiver system. And yes -- This is all done with the power off, unit unplugged, and the power supply caps safely discharged!

    Dave
     
  9. dannyr

    dannyr Active Member

    Messages:
    259
    Larry, I probably should have known to have the unit not going. I guess I got too use to adjusting the AC balance with a test tone and DVM. Thanks for the clarification so that I didn't mess up and do something extremely stupid which a real possibility. :(

    Dave, please no apology needed. I figured I'd just ask here because it I saw that it was brought up. I'm not obsessed etc. I'm curious to see if I hear the difference or not.

    Okay so the trim etc is just 96.2% of the 47k resistor pin 1 to ground. Pretty simple. Thanks!!! :)

    While I have your ear, with the phono do you just recommend rebuilding it with tight spec parts now for best performance after your 1000 experiments?

    Dan
     
    Last edited: Dec 5, 2013
  10. dcgillespie

    dcgillespie Fisher SA-100 Clone Subscriber

    Messages:
    8,865
    Location:
    Ball Ground, GA
    If phono is your game, I think it would be a worthwhile effort. The preamp has (or can have) very good conformance to the RIAA standard for all practical purposes, so I would definitely consider it.

    Good luck with it if you decide to go after it!

    Dave
     
  11. dsndblm

    dsndblm Well-Known Member

    Messages:
    950
    Location:
    Central Arizona
    This most definitely needs to be a sticky. Excellent information:thmbsp:
     
  12. IMTubeHead

    IMTubeHead OsteoFisheritis

    DAMN!! I don't know how I missed this thread, but I'm sure glad I found it!
    This is WAY COOL!! Thank you Larry & Dave for posting this info:thmbsp::banana:the infamous P. Shuff dancing banana:D
    Now...maybe sometime when either of you has the time, it would be Sooooo helpful if one or both of you(Dave or Larry)could post the alignment procedure with a VTVM or DMM only. Maybe it's already here somewhere and I missed that thread as well!! I did read in another thread that Dave mentioned using the alignment procedure shown in the Fisher KM-60(kit)Service Manual. Is this the procedure that we should use? Many thanks again :)
    Dave is SO very talented...I want to shake his hand...and YES!!!...Dave deserves an OSCAR for his work!!

    John
     
    Last edited: Dec 31, 2013
  13. larryderouin

    larryderouin Do I get Food, Med's, or more gear this Month? Subscriber

    Messages:
    19,979
    Location:
    Glen Burnie Md.
    Bump for the new guys who haven"t seen it yet!

    Kyle; Think this one needs "STICKY" Status!
     
    Last edited: Jan 27, 2014
  14. HVHiFI

    HVHiFI Hudson Valley HiFI Subscriber

    Messages:
    2,106
    Location:
    Chester, NY
    +1 :thumbup:
     
  15. larryderouin

    larryderouin Do I get Food, Med's, or more gear this Month? Subscriber

    Messages:
    19,979
    Location:
    Glen Burnie Md.
  16. larryderouin

    larryderouin Do I get Food, Med's, or more gear this Month? Subscriber

    Messages:
    19,979
    Location:
    Glen Burnie Md.
    I made a couple of edits to post #1 to alleviate confusion between earlier models and later models. Mainly part #'s.

    Larry
     
  17. Fisherdude

    Fisherdude Regular Dude - Super Mod Super Mod Subscriber

    Messages:
    27,620
    Location:
    Out West.
    Thread is stickied!

    I may have to do some consolidation in the near future, though...things are getting a bit crowded up top.
     
  18. eduarsan1

    eduarsan1 Luis Eduardo Sanchez Subscriber

    Messages:
    607
    Location:
    Bogotá, Colombia
    Fisher

    Don´t forget to stick the "improving the fisher 400" thread

    Regards!!!!
     
  19. larryderouin

    larryderouin Do I get Food, Med's, or more gear this Month? Subscriber

    Messages:
    19,979
    Location:
    Glen Burnie Md.
    Changes to 400 procedure for 800-B/C and 500-B/C

    The information on this post was edited into the original post to minimize confusion as to whether this is applicable to the 500 and 800 models. 07/31/2014


    The only real changes are which can capacitor and which section of that can cap to ground to take the measurement off pin 1 of the phase inverter tubes. It's the same section. Depending on which model you have, the B+ will either be 320VDC or 350VDC.

    As the 2nd option is the most efficacious for those of us who are technically challenged, we'll use that one for all of the following models.


    POWER OFF, PLUG BAGGED!!!! (this keeps you vertical!)

    800-C STAND-ALONE SERVICE MANUAL ALL VERSIONS
    1.) Ground C87C and follow the rest of the directions. C87C is the 350V B+. (Marker B3 at capacitor and B1 at V12)

    EXECUTIVE VIII Model 950 (800-C Serial 10001-19999)
    Procedure is same as Standalone 800-C. B+ on C87C is 320V tho.

    EXECUTIVE IX Model 960 (No Serial noted on manual).
    Procedure is same as Standalone 800-C. B+ on C87C is back up to 350VDC.


    500-C
    30001-49999 manual
    Ground C91C(350V B+) and follow directions outlined in POST #1


    500-B
    20001-29999 manual
    Ground C78C (320V B+) and follow directions outlined in POST #1


    800-B
    20001-29999 manual
    Ground C95C (320V) and follow directions outlined in POST #1
     
    Last edited: Jul 31, 2014
  20. Wharfcreek

    Wharfcreek AK Subscriber Subscriber

    Messages:
    3,696
    Location:
    Baltimore, MD
    Good Stuff Larry!

    TSD
     

Share This Page